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UW-Milwaukee Researchers Learn More About How E. Coli Impacts Beaches

Susan Bence
Some people think of a day at the beach as a perfect summer experience. UW-Milwaukee PhD candidate Natalie Rumball hopes her research helps make sure the water is safe to enjoy.

Research at UW-Milwaukee is helping us learn how E. Coli can impact beaches. Just last week, South Shore Beach was closed because of elevated levels of bacteria in the water that could make people sick.

E. coli is a bacteria found in the gut of humans and animals, which can end up in fecal matter. If a lot of that fecal matter makes its way to beaches, it becomes a public health issue. People can get sick with an upset stomach and fever.

Natalie Rumball has spent a lot of time examining the sand along Lake Michigan. She became a Ph.D., candidate in 2017 at UWM’s School of Freshwater Sciences working alongside Sandra McLellan, a leader in E. coli research.

"At the beginning of my tenure at UWM, I had more of a simplistic view of E. coli, but now the more I study the organism the more I realize that there’s a lot more variance to it,” Rumball says. "It’s found a lot more places than I would have thought and it’s able to survive a lot better from a genomic point of view, which is really important.”

Credit Susan Bence
South Shore in Bay View is one of the Milwaukee area beaches Sandra McLellan's lab has studied over the years. South Shore has chronically been closed due to poor water quality, including the day Ph.D., candidate Natalie Rumball met WUWM's Susan Bence there to talk about her E. coli research.

Rumball has focused on what scientists call "naturalized E. coli."

"What that means is that these E. coli are able to live and survive in the environment, opposed to living within a gut or within a host. They're able to be free-living and this what they're calling naturalized," she says.

To learn more about E. coli that survives in beach sand, Rumball says she took "E. coli from human sewage, some isolated from bird feces, such as from gulls, and then we isolate out the E. coli in the lab, so we grow it out."

She placed the samples in small growth chambers and then buried them at the beach for a couple of months.

Credit University of Wisconsin Sea Grant Institute
Rumball buried growth chambers containing E. coli samples at several Lake Michigan beaches in the Milwaukee area.

“We found that E. coli from all sources were able to survive,” Rumball says.

Are E. coli strains that survive in beach sand pathogenic? Basically, can they cause disease?

Rumball calls that a somewhat complicated question, that's still being studied. "But so far, what we found is that we haven't found any particular pathogenic ones that are able to survive," she says.

Rumball says taking a genomic approach to studying E. coli is critical.

"Once you’re able to understand the genomics of survival, you’re able to identify tools to be able to differentiate them. So you can take a sample of E. coli and determine is this new E. coli or old E. coli, is this E.coli specifically pathogenic or is this a strain that generally not going to hurt anybody," Rumball explains. “Did all the survivors all contain one specific gene that allow them to survive versus some of the strains that weren’t able to survive."

She hopes her research leads to improved beach monitoring methods.

“Right now it’s kind of a black or white method where it’s either 'yes' or 'no' closed. We’re trying to get more detail into why the E. coli is there, where did it come from ... So, if we understand why the E. coli is there, we’ll be able to come up with better remediation methods and better ways to protect the beaches and keep them clean,” Rumball says.

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Susan is WUWM's environmental reporter.
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